Apparatus and method for drill pipe transmission line connections

ABSTRACT

An apparatus for communicating a signal downhole includes a drill pipe configured to be rotated to drill the borehole and a tube under axial tension and secured in the drill pipe, wherein the axial tension occurs at least with the drill pipe not under axial tension. The apparatus further includes a connector sleeve sealed to an end of the tube and configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to. The apparatus further includes a transmission line configured to communicate the signal. The transmission line is disposed in the tube and has a length greater than the length of the tube and extending past the connector sleeve.

BACKGROUND

Geologic reservoirs may be used for various purposes such as hydrocarbon production, geothermal production, or carbon dioxide sequestration. These reservoirs are typically accessed by drilling boreholes through the earth to the reservoirs.

A borehole is drilled using a drill bit that is rotated by drill pipes coupled together in series and generally known as a drill string. As the borehole is being drilled, several instruments or tools disposed at the drill string may perform measurements that may be used to monitor drilling operations or characterize the earth formation being drilled. In order to provide these measurements to an operator, processing system or controller disposed at the surface of the earth in real time, these measurements may be transmitted electrically via a transmission line or cable disposed in the drill string. Because signals carrying the measurement information must traverse all of the drill pipes between the signal source and a receiver disposed at the surface of the earth, signal couplers are installed at the ends of the drill pipes. The signal couplers allow the signal to be transmitted from one drill pipe to the adjacent drill pipe that is connected to it. These couplers may be recessed into the drill pipe making it difficult to connect them to a signal transmission line, which is even further recessed in the drill pipe. Hence, apparatus and method that improves the process of making those connections would be well received in the drilling industry.

BRIEF SUMMARY

Disclosed is an apparatus for communicating a signal downhole. The apparatus includes: a drill pipe configured to be rotated to drill the borehole; a tube under axial tension and secured in the drill pipe, wherein the axial tension occurs at least with the drill pipe not under axial tension; a connector sleeve sealed to an end of the tube and configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to; and a transmission line configured to communicate the signal disposed in the tube and having a length greater than the length of the tube and extending past the connector sleeve.

Also disclosed is a method for building an apparatus for communicating a signal downhole. The method includes: selecting a drill pipe; placing a tube in axial tension, wherein the axial tension occurs at least with the drill pipe not under axial tension; securing the tube to the drill pipe using a connector sleeve that is configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to; and disposing a transmission line configured to communicate the signal into the tube, the transmission line having a length greater than the length of the tube and extending past the connector sleeve.

Further disclosed is a method for communicating a signal downhole. The method includes: disposing a drill pipe in a borehole; and communicating the signal downhole using a transmission line disposed in a tube under axial tension in the drill pipe and configured to communicate the signal, the axial tension occurring at least with the drill pipe not under axial tension wherein a connector sleeve is secured to an end portion of the tube and is configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to and the transmission line has a length greater than the length of the tube and extending past the connector sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 illustrates a cross-sectional view of an exemplary embodiment of a drill string disposed in a borehole penetrating the earth;

FIG. 2 depicts aspects of a protection tube and a connector sleeve disposed in a box end of a drill pipe;

FIG. 3 depicts aspects of the protection tube disposed in and stretched in a pin end of the drill pipe;

FIG. 4 depicts aspects of the protection tube and connector sleeve disposed in the pin end of the drill pipe;

FIG. 5 depicts aspects of a signal conductor with signal connector extending from the box end of the drill pipe;

FIG. 6 depicts aspects of a signal coupler connected to a transmission line at the box end of the drill pipe using an electrical connector;

FIG. 7 depicts aspects of a mechanical connection and a signal connection made within the connector sleeve at the box end of the drill pipe;

FIG. 8A depicts aspects of a made up signal connection before the signal coupler is inserted into a connector sleeve and FIG. 8B depicts aspects of the signal connection and signal coupler inserted into the connector sleeve, FIGS. 8A and 8B may be collectively referred to as FIG. 8;

FIG. 9 is a flow chart for a method for building an apparatus for communicating a signal to or from a downhole tool; and

FIG. 10 is flow chart for a method for communicating a signal to or from a downhole tool.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method presented herein by way of exemplification and not limitation with reference to the figures.

Disclosed are apparatus and method making connections to a signal transmission line disposed in a drill pipe. The transmission line is disposed in a tube in the drill pipe. The tube protects the transmission line from drilling fluid flowing in the interior of the signal transmission line. The signal transmission line is made purposely longer than the length of the tube. The length of the transmission line in excess of the tube length is selected to enable connection with a coupler that is configured to transmit signals to or receive signals from an adjacent coupler in an adjacent connected drill pipe. After the connection is made, the excess length of the transmission line is stored in the tube.

FIG. 1 illustrates a cross-sectional view of an exemplary embodiment of a drill string 9 disposed in a borehole 2 penetrating the earth 3, which may include an earth formation 4. The drill string 9 is made up of a series of drill pipes 8 that are coupled together. In one or more embodiments, each drill pipe 8 has a box end and a pin end where the box end of one drill pipe 8 is configured to couple to the pin end of another drill pipe 8. A drill bit 7 is disposed at the distal end of the drill string 9. A drill rig 6 is configured to conduct drilling operations such as rotating the drill string 9 and thus the drill bit 7 in order to drill the borehole 2. In addition, the drill rig 6 is configured to pump drilling fluid through the interior of the drill string 9 in order to lubricate the drill bit 7 and flush cuttings from the borehole 2. Downhole tools 10 are disposed at (i.e., in or on) the drill string 9. The downhole tools 10 are configured to perform measurements related to monitoring drilling operations and/or characterizing the earth formation 4. Accordingly, the downhole tools may include a sensor. The downhole tools 10 may also be configured to perform mechanical actions such as retrieving a formation fluid sample. Downhole electronics 11 are coupled to the downhole tools 10. The downhole electronics 11 are configured to operate the downhole tools 10, process measurement data obtained downhole, and/or act as an interface with telemetry to communicate data or commands between the downhole tools 10 and a computer processing system 12 disposed at the surface of the earth 3. The telemetry includes a transmission line 5 disposed in each drill pipe 8. Electrical communication signals are communicated between the drill pipes 8 using cooperative signal couplers that are recessed at mating surfaces of adjoining drill pipes. System operation and data processing operations may be performed by the downhole electronics 11, the computer processing system 12, or a combination thereof. The downhole tools 10 may be operated continuously or at discrete selected depths in the borehole 2.

It can be appreciated that the transmission line 5 may be configured to convey electrical signals or optical signals. To convey electrical signals, the transmission line 5 may include two or more electrical conductors, and the cooperative signal couplers may be devices or antennas for electromagnetic communication between two adjacent signal couplers. Non-limiting embodiments of the transmission line 5 for communicating electrical signals include a coaxial cable, a triaxial cable, a twisted pair cable, a ribbon cable, and insulated conductors. To convey optical signals, the transmission line 5 may include one or more optical fibers and the cooperative signal couplers may be optical couplers having optical mating surfaces recessed in the drill pipe mating surfaces.

Reference may now be had to FIG. 2 depicting aspects of a protection tube and a connector sleeve disposed in the box end of the drill pipe 8 in a cross-sectional view. Illustrated on the left side of FIG. 2 are a tube 20 and a connector sleeve 21 that is secured to the tube 20. The right side of FIG. 2 illustrates the tube 20 and the sleeve 21 being disposed within the box end of the drill pipe 8. The tube 20 traverses the drill pipe 8 from the box end to the pin end. The tube 20 is configured to contain the transmission line 5. By containing the transmission line 5, the tube 20 provides protection from the drilling fluid flowing within the drill pipe 8 and limits the range of movement of the transmission line 5 due to drill string vibration. By limiting the range of movement, the tube 20 may prevent cracks or damage from occurring in the transmission line 5 due to repetitive movement in response to drill string vibrations. As illustrated in FIG. 2, a recess 25 is in a mating surface in the box end of the drill pipe. The recess 25 is configured to accept the corresponding cooperative signal coupler so that the outer surface of the signal coupler is flush to the end face.

Two tubes 20 each secured to a connector sleeve 21 are illustrated in FIG. 2. It can be appreciated that two or more tubes may be used to provide redundancy, multiple signal paths for different types of signals or for one type of signal using one conductor in each tube to form a signal path. Alternatively, one tube may be used to contain one transmission line. For discussion purposes one tube is discussed although the following figures may illustrate two individual tubes and corresponding connector sleeves.

As illustrated in FIG. 2, the tube 20 is disposed in a bore 22 in the box end. To the right of the bore 22, the tube 20 traverses the drill pipe 8 unsupported or unrestrained until the tube 20 enters a bore at the pin end of the drill pipe 8. In an installed configuration, the tube 20 is under axial tension (i.e. having at least a vector component of axial tension), which can improve the rigidity and resistance to flexing of the tube 20, as well as abating any significant movement at the position of an electrical connector during flexure and vibration of the drill pipe. That is, the tube 20 is stretched a selected amount that is within the elastic deformation range of the tube 20 and secured in the drill pipe at each end using the connector sleeves. In one or more embodiments, a first connector sleeve is secured to one end of the tube and the tube is inserted into the bores of the drill string for accepting the tube until the installed connector sleeve engages the drill string such as at the box end. The outer diameter on the connector sleeve is generally greater than the outer diameter of the tube and the inner diameter of the bore 22 further in the drill pipe. That is, the bore 22 may have a first diameter further in the drill pipe to accommodate only the tube and a second diameter greater than the first diameter towards the end of the bore 22 to accommodate the connector sleeve surrounding the tube. Hence, the connector sleeve will engage the outside of the bore 22 preventing further movement of this end of the tube. The tube is then stretched beyond the end of a bore 32 at the pin end as illustrated in FIG. 3 and a second connector sleeve is secured to the end of the tube at this point. Once the connector sleeve is attached at the pin end, the tube is released from stretching and retracts into the bore 32 due to the elasticity of the tube until the second connector sleeve engages the drill pipe as illustrated in FIG. 4. With both connector sleeves engaged to the drill pipe, the tube remains in axial tension. As illustrated in FIG. 4, there is a recess 45 at the end face of the drill pipe at the pin end. The recess 45 is configured to accept the corresponding cooperative signal coupler so that the outer surface of the signal coupler is flush to the end face.

It can be appreciated that increasing the amount of stretching, but still being within the elastic deformation range, may increase the amount of rigidity and resistance to flexing and, thus, prevent damage from occurring in the tube 20. In addition, by resisting flexing the tube 20 may be held firmly in place so as not to interfere with tools that may be conveyed through the interior or the drill string 9. It can be appreciated that increasing the amount of stretching, but still being within the elastic deformation range, may increase the natural resonant frequency of the tube 20 such that the resonant frequency is turned or shifted in a way to prevent damage during drill string vibration.

The tube 20 and the connector sleeve 21 are made from a high strength material. The term “high strength” relates to the material having a high enough strength to be resistant to deformation during normal use. In one or more embodiments, the tube and the connector sleeves are made from a metal alloy such as a high strength stainless steel alloy. Alternatively, in one or more embodiments, the tube is made from a composite material that has an elastic deformation property. Similarly, the connector sleeves may also be made of a composite material. The materials for the tube and connector sleeves are selected to be compatible with a process for securing the connector sleeves to the tube. In one or more embodiments, the connector sleeve 21 surrounds the tube 20 where the sleeve is secured to the tube resulting in the outer diameter of the sleeve being greater than the outer diameter of the tube. Non-limiting embodiments of the securing process include welding, brazing, soldering, friction fitting, swaging, and applying an adhesive. Swaging may be performed hydraulically or by use of a ferrule. In one example of friction fitting, connector sleeves are in a cryogenic condition that expands the inner diameter of these devices. When allowed to heat up, the diameter of these devices decreases to provide the friction fit. It can be appreciated that any of these processes provides for a fluid tight seal that prevents drilling fluid from entering the tube and interfering with the transmission line.

FIG. 5 depicts aspects of the transmission line 5 extending from the box end of the drill pipe in a three-dimensional view. The length of the transmission line 5 is greater than the length of the tube plus the additional length due to the two connector sleeves. The length of the transmission line 5 extending from the connector sleeve outwards is selected to be able to make up a signal connection with a signal connector or lead from the signal coupler at the box end. In one or more embodiments, the length extending from the connector sleeve is at least the length from the connector sleeve to the end face of the drill pipe at the box end. The end of the transmission line 5 may have a signal connector 51 as shown for connection to the signal coupler or the end of the transmission line may be configured to be soldered, welded, or spliced to a signal lead extending from the signal coupler (see FIG. 6 for example).

FIG. 6 depicts aspects of a signal coupler 60 connected to the transmission line 5 at the box end of the drill pipe using an electrical connector 61 in a three-dimensional view. A first portion of the electrical connector 61 is connected to the transmission line 5 and a second portion of the electrical connector 61 is in electrical communication with the signal coupler 60. The first portion is configured to be inserted into the second portion to make an electrical connection. The transmission line 5 is illustrated in FIG. 6 with before final installation of the transmission line and the signal coupler. The transmission line extends past the end face of the box end of the drill pipe to provide sufficient length or slack for making the electrical connection before the signal coupler is inserted into the recess 25 and the excess length or slack of the transmission line is inserted into the tube.

FIG. 7 depicts aspects of a mechanical connection made between the signal coupler and the connector sleeve at the box end of the drill pipe in a cross-sectional view. The signal coupler 60 includes a mechanical connector 70 configured to be inserted into the connector sleeve 21 and seal against an inner sealing surface in the connector sleeve 21. The mechanical connector 70 includes three O-rings 71 that form a compression seal. It can be appreciated that while only one O-ring 71 is required to form a seal, the other two O-rings provide redundant seals in case one of the O-rings fail. The O-rings 71 are made of a suitable compressible material such as rubber or a fluoroelastomer that is specified to survive in the downhole environment, which can include high temperatures approaching or exceeding 200° C. and exposure to the drilling fluid.

As the signal coupler 60 is being inserted into the recess 25, the excess length or slack of the transmission line 5 is inserted into the tube 20. In one or more embodiments, the transmission line 5 rests free or has freedom of movement within the tube 20 in order to enable each end of the transmission line to be extended from either end of the tube so that signal coupler connections can be made. Another advantage of having the transmission line 5 rest free in the tube 20 is that the line in the tube can be displaced in order to make room for the slack that is being inserted into the tube as the signal coupler is being inserted into the corresponding recess. In one or more embodiments, the transmission line 5 includes a signal transmission medium (e.g., electrical conductors) that is wrapped around or woven through an elastic material such that the transmission line can be pulled to extend its length beyond the length of the tube and when released the transmission line will retract into the tube. In one or more embodiments, the transmission line 5 is a stretchable elastic electrical cord such one referred to as Roboden and available from Asahi Kasel Fibers of Japan.

FIG. 8 depicts aspects of a mechanical connection and a signal connection made at the pin end of the drill pipe. FIG. 8A illustrates a made up signal connection 80 before the signal coupler 60 is inserted into the recess 45 at the box end of the drill pipe. FIG. 8B illustrates the signal coupler 60 inserted into the connector sleeve 21 with the mechanical connector 70 sealing to the interior sealing surface of the connector sleeve 21. It can be seen that with the signal coupler 60 inserted the outer surface of the signal coupler is flush or recessed to the end face of the drill pipe at the pin end.

It can be appreciated that minimum additional tube stretching is required to attach one of the connector sleeves before the tube 20 is allowed to retract into the drill pipe 8. For example, with a drill pipe that is 30 feet long, only about two inches or 0.5% additional stretch is required to attach one of the devices using other methods to secure without the necessity of direct access like described above and would further limit the required stretch.

While the tube 20 is illustrated as being straight from the box end to the pin end of the drill pipe 8, it can be appreciated that the tube can be deviated. The tube may be deviated using restraining devices (not shown) that are configured to restrain the tube radially and yet allow the axial tension to be conveyed axially. Alternatively, the bores in the drill pipe for accepting the tube may be deviated with respect to the center line of the drill pipe.

FIG. 9 is a flow chart for a method 90 for building an apparatus for communicating a signal to or from a downhole tool. Block 91 calls for selecting a drill pipe. Block 92 calls for placing a tube is axial tension. Block 93 calls for securing the tube to the drill pipe using a connector sleeve that is configured secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to. In one or more embodiments, after one end of the tube is secured to the drill pipe using the first connector sleeve, the other tube end is stretched using a gripper device having a plier-like gripper that grips the inside and outside of the end of the tube. After the tube is stretched, a circumferential gripper grips the circumference of the tube closer to the edge of the drill pipe and the gripper device is released exposing the end so that the second connector sleeve may be secured to that end. When the circumferential gripper is released, the tube will retract back into the drill pipe until the second connector sleeve engages the drill pipe keeping the tube is axial tension. The amount of axial tension is such that the axial tension is maintained even when the drill pipe is not under axial tension or is under axial compression or bending. Block 94 calls for disposing a transmission line into the tube. The transmission line is configured to communicate a signal to or from the downhole tool and has a length that is greater than the length of the tube and is able to extend past each of the connector sleeves.

FIG. 10 is a flow chart for a method 100 for communicating a signal to or from a downhole tool. Block 101 calls for disposing a drill pipe in a borehole. Block 102 calls for communicating the signal downhole using a transmission line disposed in a tube under axial tension in the drill pipe wherein the axial tension occurs at least with the drill pipe not under axial tension. A connector sleeve is secured to an end portion of the tube and is configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to. The transmission line has a length that is greater than the length of the tube and extends past the connector sleeve. The method 100 may also include transmitting the signal between each of the drill pipes in the drill string using cooperative signal couplers.

The above disclosed techniques provide several advantages. One advantage is that having the tube under axial tension provides greater rigidity and therefore greater resistance to flexing due to drill string vibration. Another advantage to having the tube disposed in each drill pipe is to protect the transmission line from the flow of drilling fluid internal to the drill pipes.

In support of the teachings herein, various analysis components may be used, including a digital and/or an analog system. For example, the downhole tools 10, the downhole electronics 11, or the computer processing system 12 may include digital and/or analog systems. The system may have components such as a processor, storage media, memory, input, output, communications link (wired or optical or other), user interfaces, software programs, signal processors (digital or analog) and other such components (such as resistors, capacitors, inductors and others) to provide for operation and analyses of the apparatus and methods disclosed herein in any of several manners well-appreciated in the art. It is considered that these teachings may be, but need not be, implemented in conjunction with a set of computer executable instructions stored on a non-transitory computer readable medium, including memory (ROMs, RAMs), optical (CD-ROMs), or magnetic (disks, hard drives), or any other type that when executed causes a computer to implement the method of the present invention. These instructions may provide for equipment operation, control, data collection and analysis and other functions deemed relevant by a system designer, owner, user or other such personnel, in addition to the functions described in this disclosure.

Further, various other components may be included and called upon for providing for aspects of the teachings herein. For example, a power supply (e.g., at least one of a generator, a remote supply and a battery), magnet, electromagnet, sensor, electrode, transmitter, receiver, transceiver, antenna, controller, optical unit, connector, splice, electrical unit or electromechanical unit may be included in support of the various aspects discussed herein or in support of other functions beyond this disclosure.

Elements of the embodiments have been introduced with either the articles “a” or “an.” The articles are intended to mean that there are one or more of the elements. The terms “including” and “having” and the like are intended to be inclusive such that there may be additional elements other than the elements listed. The conjunction “or” when used with a list of at least two terms is intended to mean any term or combination of terms. The terms “first,” “second” and the like do not denote a particular order, but are used to distinguish different elements.

The flow diagrams depicted herein are just examples. There may be many variations to these diagrams or the steps (or operations) described therein without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted or modified. All of these variations are considered a part of the claimed invention.

While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.

It will be recognized that the various components or technologies may provide certain necessary or beneficial functionality or features. Accordingly, these functions and features as may be needed in support of the appended claims and variations thereof, are recognized as being inherently included as a part of the teachings herein and a part of the invention disclosed.

While the invention has been described with reference to exemplary embodiments, it will be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications will be appreciated to adapt a particular instrument, situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 

What is claimed is:
 1. An apparatus for communicating a signal downhole, the apparatus comprising: a drill pipe configured to be rotated to drill the borehole; a tube under axial tension and secured in the drill pipe, wherein the axial tension occurs at least with the drill pipe not under axial tension; a connector sleeve sealed to an end of the tube and configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to; and a transmission line configured to communicate the signal disposed in the tube and having a length greater than the length of the tube and extending past the connector sleeve.
 2. The apparatus according to claim 1, wherein the transmission line is elastic such that the transmission line is stretched in order to have the length of the transmission line greater than the length of the tube.
 3. The apparatus according to claim 1, wherein the connector sleeve comprises an outer diameter that is greater than an outer diameter of the tube and is configured to contact the drill pipe to maintain the tube in the axial tension.
 4. The apparatus according to claim 1, further comprising a signal coupler configured to communicate a signal with another signal coupler disposed in an adjacent drill pipe.
 5. The apparatus according to claim 4, wherein the signal coupler comprises (a) a connector configured to seal to the sealing surface of the sleeve and (b) a signal conductor configured to communicate with the transmission line.
 6. The apparatus according to claim 5, wherein the connector comprises an O-ring configured to seal against the sealing surface of the connector sleeve.
 7. The apparatus according to claim 6, wherein the sealing surface is interior to the connector sleeve.
 8. The apparatus according to claim 5, further comprising a signal connector configured to connect the transmission line to the signal conductor.
 9. The apparatus according to claim 5, further comprising at least one of a splice, weld, and solder connection configured to connect the transmission line to the signal conductor.
 10. The apparatus according to claim 3, wherein the signal coupler is recessed in a mating surface of the drill pipe.
 11. The apparatus according to claim 1, wherein the transmission line comprises at least two electrical conductors.
 12. The apparatus according to claim 1, wherein the transmission line comprises an optical fiber.
 13. The apparatus according to claim 1, wherein the connector sleeve is sealed to the tube by at least one of a weld, an adhesive, and a friction fit.
 14. The apparatus according to claim 1, wherein the connector sleeve defines an opening configured to receive the tube.
 15. A method for building an apparatus for communicating a signal downhole, the method comprising: selecting a drill pipe; placing a tube in axial tension, wherein the axial tension occurs at least with the drill pipe not under axial tension; securing the tube to the drill pipe using a connector sleeve that is configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to; and disposing a transmission line configured to communicate the signal into the tube, the transmission line having a length greater than the length of the tube and extending past the connector sleeve.
 16. The method according to claim 15, further comprising connecting a signal conductor in the connector to the transmission line using a length of the transmission line that is in excess of the tube length, wherein the signal conductor is coupled to a signal coupler configured to communicate a signal with an adjacent signal coupler disposed in an adjacent drill pipe.
 17. The method according to claim 16, wherein connecting comprises using a signal connector.
 18. The method according to claim 16, wherein connecting comprises as least one of soldering, welding and splicing.
 19. The method according to claim 16, wherein the transmission line is elastic and connecting the signal connector comprises extending the elastic transmission line in excess of the tube length.
 20. The method according to claim 19, further comprising retracting the elastic transmission line into the tube using the elasticity of the elastic transmission line.
 21. The method according to claim 15, further comprising sealing the connector to the connector sleeve with a fluid tight connection.
 22. The method according to claim 21, wherein sealing comprises using an O-ring.
 23. A method for communicating a signal downhole, the method comprising: disposing a drill pipe in a borehole; and communicating the signal downhole using a transmission line disposed in a tube under axial tension in the drill pipe and configured to communicate the signal, the axial tension occurring at least with the drill pipe not under axial tension wherein a connector sleeve is secured to an end portion of the tube and is configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to and the transmission line has a length greater than the length of the tube and extending past the connector sleeve. 